This invention relates generally to displays for electronic devices such as computers.
Liquid crystal displays (LCD) are used as the displays for a large number of electronic devices including laptop computers, telephones, desktop computers, and televisions. However, the predominant display technology continues to use cathode ray tubes (CRT). Most displays today are designed to interface with the older analog technology standards.
Typical CRTs use a raster update interface. This means that pixels must be repeatedly traced in a linear fashion from left to right across the display and from top to bottom. This scanning occurs at a relatively high rate because the image elements of the CRT glow for only a short period of time. Thus, these image elements or phosphors must be frequently refreshed in order to give the appearance of constant light.
Because of the prevalence and widespread acceptance of CRTs as displays for electronic devices, most displays, including liquid crystal displays, tend to match the CRT interface paradigm. Thus, most displays are not designed to have their images persist for a relatively longer time because the raster interface paradigm guarantees that the image is quickly refreshed.
The display refresh controller which provides the refresh signals for the display may use an interface bus that is also used by a graphics processor and general purpose microprocessor in the host system. In addition, the controller may make use of the system memory that other system level devices utilize. Thus, the continuing demands for display refresh tend to tax the available system resources. This means that some portion of the available system bandwidth must be dedicated to supporting the display refresh operation. This may adversely affect bandwidth and potentially decrease system performance.
The need to periodically refresh the information in the display takes up some of the bandwidth that could be used to increase the resolution of the display. In addition, some of the available bandwidth could be used to provide higher rate images if that bandwidth were not consumed in supplying redundant information to the display.